I am advised by Revenue that a Costs of Tax Expenditures Table is available on the Revenue Statistics webpage at http://www.revenue.ie/en/about/statistics/costs-expenditures.html.
This table provides an annual breakdown of the numbers availing of the credit and the cost to the Exchequer for the ‘Blind Person's or Civil Partners Credit (including Guide Dog Allowance)' for each of the years 2004 to 2014, the latest year for which data are available. The table will be updated in due course as newer data become available.